Among community-living older persons, disability in essential activities of daily living, such as bathing, dressing, walking, and transferring, is common, highly morbid, and costly. During the current funding period, we have provided strong evidence to support an emerging paradigm of disability as a reversible, and often recurrent, event. We have also demonstrated that illnesses and injuries leading to either hospitalization or restricted activity represent important sources of disability and that habitual physical activity is an independent predictor of both time to and duration of recovery of independent function. The overall objective of this renewal application is to further elucidate the epidemiology of disability and recovery among older persons, with particular emphasis on disability subtypes and on disability transitions among persons admitted to a nursing home and at the end of life. We propose 3 linked sets of primary specific aims and hypotheses, complemented by a set of 3 secondary aims. The premise underlying the proposed research is that disability is a complex and highly dynamic process with considerable heterogeneity and multiple potential pathways. The inherent complexity of disability has historically not been well appreciated, largely because prior longitudinal studies have almost invariably included long intervals, ranging from 6 months to 6 years, between disability assessments. To accomplish our specific aims and test our hypotheses, we will use high quality data from the Yale PEP Study, a unique and highly innovative, ongoing study of 754 initially nondisabled, community-living persons, aged 70 years or older, with a median follow-up (to date) of 67 months. Participants have completed comprehensive home-based assessments at baseline and, subsequently, at 18-month intervals and have been followed monthly via telephone interviews to reassess their functional status, ascertain potential intervening events, and identify admissions to the nursing home and deaths. The research proposed in this renewal application addresses a fundamental problem in geriatric medicine and gerontology and builds upon a large body of work that has been completed during the current funding period. By further elucidating the epidemiology of disability and recovery among older persons, the proposed research will help to inform the development of effective and efficient interventions designed to maintain and restore independent function among older persons.